Composite flow moulding

Endolign - This is an implantable continuous carbon fibre composite which is used for the replacement of metals in high sustained or cyclic load applications. The ability to control fibre direction means that mechanical properties can be tailored for specific applications. It is supplied as a pre-impregnated tape or as rods that can be heat-formed through processes such a composite flow moulding. 

In some moulding compositions other special purpose ingredients may be incorporated. For example, naphthalene, furfural and dibutyl phthalate are occasionally used as plasticisers or more strictly as flow promoters. They are particularly useful where powders with a low moulding shrinkage are required. In such formulations a highly condensed resin is used so that there will be less reaction, and hence less shrinkage, during cure. The plasticiser is incorporated to... 

Injection moulding compositions have a number of requirements with regard to granule flow and cure characteristics not always met by conventional formulations. For example, granules should be free-flowing (i.e. of a narrow particle size distribution and not too irregular in shape). There are also certain requirements in terms of viscosity. 

The composition comprises, per 100 pbw, from 60 to 90 pbw of a propylene homopolymer (A) having a melt flow index from 0.1 to 20 g/10 min and from 40 to 10 pbw of a propylene random copolymer (B) containing from 3 to 20 mol % of ethylene and/or an alpha-olefin having from 4 to 6 carbon atoms, the melt flow index of which ranges from 25 to 3000 g/10 min. It is used in the manufacture of expanded granules and moulded cellular articles. 

Fig.36. Variation in electrical conductivity (o) with molecular weight for polyethylene composites filled with 4% by volume carbon black, demonstrating the effects of orientation (I), degradation (II) and flow-induced segregation of carbon black aggregates (III). ( ) injection moulded (O) compression moulded (unoriented) [181]...

This definition again invites further comment and elaboration. The implication may be that finishing is begun after a product is shaped by flow , but this is not always the case and the surfaces of many products are finished in part while compositions are hot or warm still. It mentions as examples six techniques for finishing but the Standard itself includes many more than this and it is worth remembering too that intermediates such as film, sheet, and mouldings (which require further fabrication before they become plastic products ) also must be finished satisfactorily the properties of the surface of an intermediate can be essential in obtaining the results required in the ultimate product. 

The mouldability index is the length of the elongated flow path that is filled before solidification of the injected molten polymer composition at specified moulding conditions, i.e., volumetric injection rate, mould temperature, polymer melt temperature. The mouldability index of the moulding compositions of this invention is characterised by spiral flow. 

Now let us discuss the case of non-isothermic flows when the channel walls temperature is lower than the composition phase transfer temperature. This is a common situation for filling moulding forms. In [18, 19, 32] this is realized by filling the snail spiral form. Before filling, the form was kept at room temperature. After filling, the form was taken apart. The length of the melt L was measured. 

In this paper, all the blends and composites are designated by the type of matrix (G for the neat nylon, D for the 8 wt % rubber-modified nylon and N for the 20 wt % rubber-modified nylon), the concentration of fibres and the type of fibre/matrix interface (A or B). As an example, a material designed DlOB is a ternary blend made of DZ matrix and 10 wt% of type B fibres. After drying the specimens for 24 hours at 100°C, they were stored in plastic bags inside a desiccator. In comparison with freshly injection moulded samples, the moisture content in the specimens ready for mechanical testing is about 2 wt%. All the mechanical tests were conducted in an environmental chamber in controlled conditions a temperature of 20°C under a continuous argon flow. 

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